The invention relates to a microscope having at least one beam path and an optical system along an optical axis, and having a fade-in element for reflecting in image information for an observer""s eye. Microscopes in the sense of the invention are to be understood principally, but not exclusively, as devices which have a main objective, a tube and an eyepiece for looking into. In the widest understanding of the invention, therefore, all other optically magnifying devices are to be understood which are directed onto an object to be magnified and make visible to the observer""s eye a magnified image of the object observed. Microscopes, in particular stereomicroscopes, for example surgical microscopes, in particular also video (stereo) microscopes which are connected to an electronic data processing unit and/or a display are comfortable for a user when the latter is not exclusively dependent on the image currently seen through the main objective of the microscope, but also obtains when looking into the tube of the microscope additional information which is generally superimposed on the currently seen image. This can be graphic characters, symbolic representations, marks, but also superimposed images of the same object which are obtained, for example, with the aid of image processing software from the currently seen object or by means of other visualizing measures (for example X-ray pictures, CT etc.) from the same object.
Microscopes with fade-in possibilities or image superimposition possibilities are also used, inter alia, in technology, for example materials engineering, material analysis, silicon technology, criminology, etc., but also, in particular, in medicine for diagnosis, serological examinations, during operations etc.
Chiefly in the case of surgical microscopes and, in particular, during an operation, a quantity of information arises which can be of great importance to the surgeon. This is, for example, information on the patient or his state of health or patient parameters such as pulse, blood pressure, oxygen content of the blood, etc. These are in addition to the currently observed superimposing images, for example, information on specific parameters of the microscope, information on the position of the observed operation zone, as well as control data which, for example, the surgeon delivers at will via control elements such as a computer mouse or foot switch to the data processing device or to control elements for the microscope, in order to control the latter as required, for example to focus it, etc.
The use of the invention in the field of surgical microscopy will be taken up below by way of example. The invention is also applicable in other fields.
Surgical microscopes are used by the operating surgeon for optical magnification of the operation zone. Operation technology is so far advanced in this connection that magnifications in the region of 50 fold and above are no rarity. It is important during an operation that the all important information is transmitted to the operating surgeon as quickly and unambiguously as possible, in order for him to be able to conclude the operation in as short a time as possible. Since the operating surgeon preferably removes his eyes as little as possible from the eyepiece of the surgical microscope, and, conversely, difficulties of comprehension can be expected with the spoken word, it is obvious for important information such as, for example, patient data, micoscope control data or positional data to be rendered visible in the tube.
This is achieved according to known techniques by representing the relevant information on a display and reflecting the image of this display into the tube via a beam splitter. Because the user always wants a good light yield for the object observed, which can frequently be ensured by high illumination densities at the object, the problem of adequate optical density of the image reflected in or superimposed often arises in the case of reflecting in. In this case, tube displays (CRT) frequently provide no way out. The use of LCDs with strong background illuminations is attended by disadvantages in the field of resolution and also in attempting to reproduce thin lines, also since the pixel width of the LCDs is relatively large, and therefore relatively wide minimum line thicknesses are prescribed. Moreover, LCD pixels form rasters which can produce problems with edge definition and resolution.
If it is now desired, for example, to have edge improvements, image colorings, contrast improvements or other marks which are as thin as possible, and which have been prepared, for example, after prior recording by means of video technology and by means of electronic image processing, it can happen disadvantageously that the known possibilities produce unsatisfactory performance with regard to brightness and/or line thickness. Contouring would be desirable, but not achievable optimally using the means of the prior art.
A special field for the superimposition of images rises, for example, in the application of computer tomography (CT) or magnetic resonance imaging (MRI) in conjunction with stereomicroscopy. Data are obtained from CT and MRI in order to obtain a sectional image of the zone of interest from the patient which, in the final analysis after EDP, permits the representation on a computer monitor (stereo display screen) of a three-dimensional model which is faithful to reality. By using such three-dimensional images, the attending doctors are better able to localize the type and spread of the diseased area. However, it is frequently the case that both the image currently seen and the available three-dimensional representation of X-ray or CT image data are not clear enough for the relevant area to be identified during operation in a marked-off fashion with sufficient clarity from the remaining region.
As already mentioned, contour reworking or contour representation suffice for this identification to be performed optimally, but these are to be as bright and thin as possible in order not to cover other details.
Accomplishing this is one of the main objects on which the invention is based.
This object is achieved, for example, by utilizing the method and device described herein.
The problems described are eliminated by superimposing onto a first image, seen through the main objective (8) of a microscope, such as shown in FIG. 1, at least one second image from a thin, focused light beam, in particular a laser beam which is deflected and/or modulated in a deflecting device and reflected into the beam path of the microscope via a fade-in element in such a way that it visibly represents the second image for an observer""s eye. A thin light beam, in particular a laser beam, can be generated in virtually arbitrarily thin and bright fashion.
It is relatively easy for the components newly required for this in accordance with the invention to be integrated into a microscope. Fade-in elements, suitable light sources, in particular lasers, are known per se to the person skilled in the art. However, despite their favorable properties, they have evidently not been used so far for the effects being sought in the field of microscopy.
It is not important here for the purpose of the invention whether the thin light beam or laser beam is projected by the optical system directly onto the retina or onto an interposed diffusing screen, or else directly in the other direction onto the object itself, in order to represent the corresponding marking there on the object surface.
Within the scope of the invention, there are both variants in which, in the operating state, the light beam extends in the region of an intermediate image plane of the optical system in a fashion approximately parallel to the optical axis in the direction of the eyepiece, and variants in which a diffusing screen on which the light beam can be scattered is arranged in the intermediate image plane.
For the purpose of the invention, a diffusing screen is in this case any optical element on which a thin light beam is scattered upon impingement in such a way that its point of contact can be seen from different points of view. Thus, this could also be an uncoated glass plate. However, it can also be, for example, a beam splitter to which a scattering coating is applied to a surface inside the optical system, or one surface of which is roughened.
According to the invention, any desired pictorial information can be fed to the observer by means of a light beam and deflecting device. In accordance with a specific embodiment of the invention, the deflecting device and/or the light source is controlled by an image processing device for contour representation, which is coupled to an image recording device which is coupled to the optical system via a further fade-in element. This permits direct feedback between the image of the object which is seen and the image represented by means of the beam. This variant is advantageous by virtue of the brightness of a focused light beam. Despite a bright operating field of view, the area to be emphasized is seen by the operating surgeon in a clearly highlighted fashion. This is so, of course, even in the case of variants in which not only the image seen optically is the basis for the image representation of the beam, but also the diagnostic data, acting as though at the same object position, from a diagnostic data device (for example a CT, MRI, PE device or the like).
In the latter variants, it is preferred to provide in each case at least one beam path per observer""s eye (stereomicroscope), it being the case that in each beam path in each case one left-hand and right-hand item of partial image information, which are offset in terms of perspective in relation to the respective other one can be reflected in from one, or in each case one deflecting device via a fade-in element in each case, the deflecting device(s) being controlled by an image recognition and/or image processing device.
An image recognition device is to be understood as a system which is able to recognize the identity of the objects observed through different observation units, and in this way enables image data to be superimposed in the correct position. For this purpose, reference is made expressly to Swiss Patent Application CH3932194-0 (corresponding to WO 9620421) of the applicant, in which a particularly suitable device is described in which image data can be corrected not only for correct position but also optically and be superimposed in a fashion matched to one another. A combination of the two inventions is advantageous.
The preferred method is yielded in this connection when the deflecting device is controlled by image information obtained from the object observed through the microscope, so that, for example, contours of object details are retraced, or object details are represented by means of grid lines or the like at the actual site of the object detail in the visual field area. Of course, such grid lines have the ideal effect principally in the case of stereomicroscopes when they are used to retrace a specific object detail (for example a tumor) in three dimensions or in plastic terms.
In accordance with a development of the invention, a continuously controllable light valve is placed in front of the light source, so that a user can regulate the brightness of the image faded in by means of the beam. When conventional lamps are used, it is also possible, of course, for their brightness to be regulated via the power supply. In the case of lasers, in particular, however, the abovementioned variant is to be recommended.
Operating convenience is enhanced if the light color of the light source or of the laser can also be adjusted, something which is possible by measures known to experts in light sources or lasers.
Further advantages follow in accordance with further special embodiments of the invention in which the image observed (background image) exerts a reaction on the superimposed image. According to the invention, the procedure here is based on two points of view: relative brightness of individual pixels with respect to one another, and total brightness of the image, limited by possible adaptation behavior.
Swiss Patent Application CH1091/94-3 (corresponding to WO 9527917, WO 9527918, US 5,841,149, US 5,953,114, and US 6,043,890) describes an arrangement which permits super-impositions and data adaptations mentioned above to be enabled as quickly as possible or in real time. A combination of the present teaching with the teaching of the abovementioned application therefore provides further advantages. To this extent, the content of the abovementioned patent application is considered as being within the scope of the present disclosure.